With advancement in geological exploration drilling technologies, the requirements for the performance of drilling tools used in oil drilling are higher and higher, and the working conditions the oil drilling bits deals with are increasingly complex and poor. Accordingly, the requirements for wear resistance of wear-resistant deposit-welding layers on the bits are higher and higher.
There are multiple areas on the bits that require improvement on wear resistance. In terms of working conditions and wear resistance of the bit, on the one hand, high wear resistance under low stress is required, which usually can be measured and evaluated based on ASTM G65 standard; on the other hand, high wear resistance under high stress is required, which usually can be measured and evaluated based on ASTM B611 standard. According to complexity of the working conditions of the bit, different parts of the bit can be applied with different deposit-welded welding rods that have different performance characteristics, such that the overall performance of the bit can be improved. For wear-resistant tube welding rods under high stress, a wear-resistant phase of the filler in the wear-resistant tube welding rods has undergone continuous improvement of sintered tungsten carbide particles, spherical sintered tungsten carbide particles, and the combination of spherical sintered tungsten carbide particles and crushed cast tungsten carbide. Chinese Patent No. 200810155754.9 proposes a technology using the combination of spherical sintered tungsten carbide particles, surface treated cast tungsten carbide, and spherical cast tungsten carbide, so that the performance of such a type of tube welding rod has been greatly improved. However, it is still an urgent need to further design optimized welding rod filler to enhance and perfect the wear resistance and welding property of the tube welding rod under high stress state.